In recent years, a vehicle seat core member formed by integrating a reinforcing member made of, for example, metal, a securing attachment for securing a seat to a vehicle, and a molded article of expanded beads (hereinafter may be referred to simply as a molded article) has been used for cars.
In such a vehicle seat core member formed by integrating a molded article of expanded beads, a reinforcing member, and other parts, the reinforcing member is embedded in the molded article of expanded beads made of thermoplastic resin. Specifically, the core member is formed by positioning a metal frame integrated with a connecting protrusion serving as a securing attachment in a mold for molding expanded beads, loading expanded beads in the mold, and then performing foam molding (see page 6 and FIG. 3 in Patent Literature 1). In this manner, a vehicle seat core member including a connecting protrusion projecting from the bottom of a molded article of expanded beads and a metal frame of which portion is embedded in the molded article of expanded beads is provided. When using the seat core member, the connecting protrusion, which is the securing attachment, is connected to a stopper of the vehicle to secure the seat to a vehicle.